• Restorative Dentistry and Endodontics
• /
• 제42권1호
• /
• pp.34-38
• /
• 2017

Objectives: The aim of this study was to evaluate the cyclic fatigue resistance of the ProTaper Universal D1 file (Dentsply Maillefer) under continuous and adaptive motion. Materials and Methods: Forty ProTaper Universal D1 files were included in this study. The cyclic fatigue tests were performed using a dynamic cyclic fatigue testing device, which had an artificial stainless steel canal with a $60^{\circ}$ angle of curvature and a 5 mm radius of curvature. The files were randomly divided into two groups (Group 1, Rotary motion; Group 2, Adaptive motion). The time to failure of the files were recorded in seconds. The number of cycles to failure (NCF) was calculated for each group. The data were statistically analyzed using Student's t-test. The statistical significant level was set at p < 0.05. Results: The cyclic fatigue resistance of the adaptive motion group was significantly higher than the rotary motion group (p < 0.05). Conclusion: Within the limitations of the present study, the 'Adaptive motion' significantly increased the resistance of the ProTaper Universal D1 file to cyclic facture.

• Restorative Dentistry and Endodontics
• /
• 제42권4호
• /
• pp.332-341
• /
• 2017

Objectives: To determine the incidence of crack formation and propagation in apical root dentin after retreatment procedures performed using ProTaper Universal Retreatment (PTR), Mtwo-R, ProTaper Next (PTN), and Twisted File Adaptive (TFA) systems. Materials and Methods: The study consisted of 120 extracted mandibular premolars. One millimeter from the apex of each tooth was ground perpendicular to the long axis of the tooth, and the apical surface was polished. Twenty teeth served as the negative control group. One hundred teeth were prepared, obturated, and then divided into 5 retreatment groups. The retreatment procedures were performed using the following files: PTR, Mtwo-R, PTN, TFA, and hand files. After filling material removal, apical enlargement was done using apical size 0.50 mm ProTaper Universal (PTU), Mtwo, PTN, TFA, and hand files. Digital images of the apical root surfaces were recorded before preparation, after preparation, after obturation, after filling removal, and after apical enlargement using a stereomicroscope. The images were then inspected for the presence of new apical cracks and crack propagation. Data were analyzed with ${\chi}^2$ tests using SPSS 21.0 software. Results: New cracks and crack propagation occurred in all the experimental groups during the retreatment process. Nickel-titanium rotary file systems caused significantly more apical crack formation and propagation than the hand files. The PTU system caused significantly more apical cracks than the other groups after the apical enlargement stage. Conclusions: This study showed that retreatment procedures and apical enlargement after the use of retreatment files can cause crack formation and propagation in apical dentin.

• 구강회복응용과학지
• /
• 제38권4호
• /
• pp.213-221
• /
• 2022

목적: 근관 치료에 사용된 실러의 양과, 재치료용 NiTi 파일이 근관충전재의 제거 효율에 미치는 영향을 알아보고자 하였다. 연구 재료 및 방법: 발거된 소구치 중 단일 근관을 가지는 치아를 대상으로 하였다. #40/.06까지 근관 형성을 한 후, 무작위로 4 그룹으로 분류하였다. 근관충전재 중 실러가 차지하는 양을 다르게 하기 위해 그룹 별로 .06 taper 또는 .04 taper 거타퍼차를 칼슘실리케이트 실러인 Ceraseal과 함께 사용하여 single-cone 충전법으로 충전하였다. 그룹 별로 재치료용 NiTi 파일로는 ProTaper Universal Retreatment system (PTUR) 또는 Hyflex Remover (HR)를 사용하였다. 충전재 제거에 걸린 시간, 치근단 방출 잔사량, 근관 내의 충전재 잔존량을 측정하고 비교하였다. 결과: 근관치료에 사용된 실러의 양은 충전재 제거 효율에 영향을 미치지 않았다. HR 그룹은 PTUR 그룹보다 빠르게 충전재를 제거하였다. 치근단 방출 잔사량과 근관충전재 잔존량은 재치료용 NiTi 파일의 종류에 따라 유의한 차이를 보이지 않았다. 결론: 근관치료에 사용된 실러의 양은 제거 효율에 유의한 영향을 미치지 않았다. HR는 기존의 PTUR보다 빠르게 충전재를 제거했으며, 다른 제거 효율은 차이가 없었다.

• Restorative Dentistry and Endodontics
• /
• 제46권1호
• /
• pp.5.1-5.13
• /
• 2021

Objectives: The aim of the current study was to assess whether the amount of extruded debris differs for straight and severely curved root canals during retreatment using H-files, R-Endo, Reciproc and ProTaper Universal Retreatment (PTU-R) files. Additionally, the area of residual filling material was evaluated. Materials and Methods: Severely curved (n = 104) and straight (n = 104) root canals of maxillary molar teeth were prepared with WaveOne Primary file and obturated with gutta-percha and AH Plus sealer. Root canal filling materials were removed with one of the preparation techniques: group 1: H-file; group 2: R-Endo; group 3: Reciproc; group 4: PTU-R (n = 26). The amount of extruded material and the area of the residual filling material was measured. The data were analyzed with 2-way analysis of variance (ANOVA) and 1-way ANOVA at the 0.05 significance level. Results: Except for Reciproc group (p > 0.05), PTU-R, R-Endo, and H-file systems extruded significantly more debris in severely curved canals (p < 0.05). Each file system caused more residual filling material in severely curved canals than in straight ones (p < 0.05). Conclusions: All instruments used in this study caused apical debris extrusion. Root canal curvature had an effect on extruded debris, except for Reciproc system. Clinicians should be aware that the difficult morphology of the severely curved root canals is a factor increasing the amount of extruded debris during the retreatment procedure.